Hi,
I'd like to offer the following bugfix under BSD licence:
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== The patch ==
At file:///home/psergey/dev/mysql-next-fix-subq/
------------------------------------------------------------
revno: 2817
revision-id: psergey@stripped
parent: psergey@stripped
committer: Sergey Petrunya <psergey@stripped>
branch nick: mysql-next-fix-subq
timestamp: Mon 2009-07-06 18:33:29 +0400
message:
BUG#42742: crash in setup_sj_materialization, Copy_field::set
- If a semi-join strategy covers certain [first_table; last_table]
range in join order, do reset the sj_strategy member for all tables
within the range, except the first one.
Failure to do so caused EXPLAIN/execution code to try applying two
strategies at once which would cause all kinds of undesired effects.
=== modified file 'mysql-test/r/subselect_sj2.result'
--- a/mysql-test/r/subselect_sj2.result 2009-03-21 15:31:38 +0000
+++ b/mysql-test/r/subselect_sj2.result 2009-07-06 14:33:29 +0000
@@ -689,3 +689,19 @@
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const
tables
drop table t1, t2;
+#
+# BUG#42742: crash in setup_sj_materialization, Copy_field::set
+#
+create table t3 ( c1 year) engine=innodb;
+insert into t3 values (2135),(2142);
+create table t2 (c1 tinytext,c2 text,c6 timestamp) engine=innodb;
+# The following must not crash, EXPLAIN should show one SJ strategy, not a mix:
+explain select 1 from t2 where
+c2 in (select 1 from t3, t2) and
+c1 in (select convert(c6,char(1)) from t2);
+id select_type table type possible_keys key key_len ref rows Extra
+1 PRIMARY t2 ALL NULL NULL NULL NULL 1 Using where
+1 PRIMARY t2 ALL NULL NULL NULL NULL 1
+1 PRIMARY t2 ALL NULL NULL NULL NULL 1 Using where; Using join buffer
+1 PRIMARY t3 ALL NULL NULL NULL NULL 2 FirstMatch(t2); Using join buffer
+drop table t2, t3;
=== modified file 'mysql-test/r/subselect_sj2_jcl6.result'
--- a/mysql-test/r/subselect_sj2_jcl6.result 2009-06-19 09:12:06 +0000
+++ b/mysql-test/r/subselect_sj2_jcl6.result 2009-07-06 14:33:29 +0000
@@ -693,6 +693,22 @@
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const
tables
drop table t1, t2;
+#
+# BUG#42742: crash in setup_sj_materialization, Copy_field::set
+#
+create table t3 ( c1 year) engine=innodb;
+insert into t3 values (2135),(2142);
+create table t2 (c1 tinytext,c2 text,c6 timestamp) engine=innodb;
+# The following must not crash, EXPLAIN should show one SJ strategy, not a mix:
+explain select 1 from t2 where
+c2 in (select 1 from t3, t2) and
+c1 in (select convert(c6,char(1)) from t2);
+id select_type table type possible_keys key key_len ref rows Extra
+1 PRIMARY t2 ALL NULL NULL NULL NULL 1 Using where
+1 PRIMARY t2 ALL NULL NULL NULL NULL 1 Using join buffer
+1 PRIMARY t2 ALL NULL NULL NULL NULL 1 Using where; Using join buffer
+1 PRIMARY t3 ALL NULL NULL NULL NULL 2 FirstMatch(t2); Using join buffer
+drop table t2, t3;
set join_cache_level=default;
show variables like 'join_cache_level';
Variable_name Value
=== modified file 'mysql-test/t/subselect_sj2.test'
--- a/mysql-test/t/subselect_sj2.test 2009-03-21 15:31:38 +0000
+++ b/mysql-test/t/subselect_sj2.test 2009-07-06 14:33:29 +0000
@@ -872,3 +872,15 @@
explain select 1 from t2 where c2 = any (select log10(null) from t1 where c6 <null) ;
drop table t1, t2;
+--echo #
+--echo # BUG#42742: crash in setup_sj_materialization, Copy_field::set
+--echo #
+create table t3 ( c1 year) engine=innodb;
+insert into t3 values (2135),(2142);
+create table t2 (c1 tinytext,c2 text,c6 timestamp) engine=innodb;
+-- echo # The following must not crash, EXPLAIN should show one SJ strategy, not a mix:
+explain select 1 from t2 where
+ c2 in (select 1 from t3, t2) and
+ c1 in (select convert(c6,char(1)) from t2);
+drop table t2, t3;
+
=== modified file 'sql/sql_select.cc'
--- a/sql/sql_select.cc 2009-07-06 07:57:39 +0000
+++ b/sql/sql_select.cc 2009-07-06 14:33:29 +0000
@@ -7916,7 +7916,11 @@
uint i_end= first + join->best_positions[first].n_sj_tables;
for (uint i= first; i < i_end; i++)
+ {
+ if (i != first)
+ join->best_positions[i].sj_strategy= SJ_OPT_NONE;
handled_tabs |= join->best_positions[i].table->table->map;
+ }
if (tablenr != first)
pos->sj_strategy= SJ_OPT_NONE;
BR
Sergey
--
Sergey Petrunia, Software Developer
Monty Program AB, http://askmonty.org
Blog: http://s.petrunia.net/blog
